The Insulin tolerance test is recognized as the gold standard assay of adrenal insufficiency, but due to the cumbersome requirement for a two-hour test and the risks of seizures or myocardial infarction, the ACTH stimulation test is commonly used as an easier, safer, though not as accurate, alternative. In addition to quantifying adrenal insufficiency, the test can distinguish whether the cause is adrenal (low cortisol and aldosterone production) or pituitary (low ACTH production). This test is used to diagnose or exclude primary and secondary adrenal insufficiency, Addison's disease, and related conditions. This test may cause mild side effects in some individuals. ĭuring the test, a small amount of synthetic ACTH is injected, and the amount of cortisol (and sometimes aldosterone) that the adrenals produce in response is measured.

ACTH is a hormone produced in the anterior pituitary gland that stimulates the adrenal glands to release cortisol, dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEA-S), and aldosterone. The ACTH test (also called the cosyntropin, tetracosactide, or Synacthen test) is a medical test usually requested and interpreted by endocrinologists to assess the functioning of the adrenal glands' stress response by measuring the adrenal response to adrenocorticotropic hormone (ACTH corticotropin) or another corticotropic agent such as tetracosactide (cosyntropin, tetracosactrin Synacthen) or alsactide (Synchrodyn).

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